Through his account of the cardinal role of the principle of permission in a secular pluralist society, H. Tristram Engelhardt, Jr. has established an ethic of non-substantive liberalism, which he usually terms "a content-less secular morality." Unlike versions of substantive liberalism, what he offers is a pure procedural principle concerning moral and political authority. In this essay I will argue that versions of substantive liberalism cannot be justified through sound rational argument. Consequently, an Engelhardtian non-substantive secular morality is morally unavoidable in the contemporary world.